Sagittarius B2 (Sgr B2), the massive star-forming region located close to the Galactic Center, is known as one of the best hunting grounds for complex organic molecules in the interstellar medium. Many prebiotic molecules have been detected in Sgr B2. Observations using the Shanghai Tianma 65m telescope have revealed widespread complex organic molecules around Sgr B2. However, the abundant emissions caused serious line-blending in Sgr B2 and made identifying new molecules in Sgr B2 particularly difficult. Recently, an international group led by Juan Li from Shanghai Astronomical Observatory and Xing Lu from the National Astronomical Observatory of Japan, reported the detection of propionamide (C2H5CONH2) toward Sgr B2 for the first time with the Atacama Large Millimeter/submillimeter Array (ALMA). This is the largest peptide-like molecule detected in space. Based on the high resolution and high sensitivity ALMA data, they find a possible propionamide transition whose intensity and velocity are consistent with simulations. The detection of propionamide in Sgr B2 demonstrates that interstellar chemistry can reach sufficient levels of complexity to form relatively large peptide molecules and shows the possible growth of larger amide molecules from smaller ones in a massive star-forming process. Propionamide might also exist in massive star-forming regions in the Galactic disk, such as Orion KL. Future ALMA observations can reveal its presence. Reference: “Propionamide (C2H5CONH2): The Largest Peptide-like Molecule in Space” by Juan Li, Junzhi Wang, Xing Lu (吕行)3, Vadim Ilyushin4,5, Roman A. Motiyenko6, Qian Gou (勾茜)7, Eugene A. Alekseev4,5, Donghui Quan (全冬晖)8,9, Laurent Margulès6, Feng Gao (高峰)10,11, Frank J. Lovas12,13, Yajun Wu (吴亚军)1,2, Edwin Bergin14, Shanghuo Li (李尚活)15, Zhiqiang Shen (沈志强)1,2, Fujun Du (杜福君)16,17, Meng Li (李梦)7, Siqi Zheng (郑思琪)1,2,18, and Xingwu Zheng, 16 September 2021, The Astrophysical Journal.DOI: 10.3847/1538-4357/ac091c
